Over 3000 acres of bell pepper are grown annually in New Jersey for fresh market and processing production (Rutgers University, 2005). Bell pepper production in New Jersey represents 5.5% of the total U.S. production acreage with an estimated value of $33 million [U.S. Department of Agriculture (USDA), 2011]. Each year, commercial vegetable production recommendations are distributed to vegetable growers in New Jersey and other states in the mid-Atlantic region (Pennsylvania, Delaware, Maryland, and Virginia) to use as a guideline for crop management (Orton, 2011). In recent years, the recommendation for nitrogen fertilization of bell pepper in New Jersey has been to apply 180 lb/acre, with 60 lb/acre broadcast and incorporated before bed formation followed by an additional 120 lb/acre split evenly through weekly drip irrigation during the production season (Orton, 2011). However, in some instances, bell pepper growers in southern New Jersey have increased fertilizer application rates up to 300 lb of N per mulch acre because of the very porous, sandy Atlantic coastal plain soils of southern New Jersey.
A methylene urea slow-release polymer-based fertilizer called Nitamin® (Georgia-Pacific Resins, Decatur, GA) in a granular formulation (Nitamin-43G®) or liquid formulation (Nitamin-30L®) has been developed to supply nitrogen to vegetable crops. The granular formulation consists of 43% water-soluble N with 30% of the N in the form of methylene urea polymers and 70% as urea, and the liquid formulation consists of 60% of the N as methylene urea polymers and 40% of the N as urea. The fertilizer releases nitrogen by microbial decomposition and is completely soluble in water (Reyes et al., 2008). Several case studies have been conducted to determine the effects of the fertilizer on vegetable crop yield. In a Georgia study, marketable yield of bell pepper was as good as or better than that in the standard program when the fertilizer was used in combination with quick-release N materials, or when the total N rate was split with Nitamin® applications (Kelley, 2005). In a Texas study, the fertilizer improved tomato yield at lower rates with fewer applications compared with the standard practice resulting in a gross return of $970–$4563 per acre (Dainello, 2006). Studies in Delaware determined that the fertilizer applied preplant to corn did not provide superior performance to a split application of urea ammonium nitrate solution (Alley et al., 2006). The use of the fertilizer as a slow-release source of N in a North Carolina bell pepper production study showed potential use across the state at reduced rates and had a greater impact on yield in the coarse-textured soils of the eastern coastal plain region (Reyes et al., 2008).
Phytophthora capsici is a serious pathogen of solanaceous and cucurbit crops in many vegetable production regions of the United States (Ristaino and Johnston, 1999). The crown rot phase of phytophthora blight can cause substantial economic losses on some farms in New Jersey each year. Since P. capsici can be found on most vegetable farms in the southern region of the state, many bell pepper growers in New Jersey plant phytophthora-tolerant cultivars. Some commonly grown bell pepper cultivars in New Jersey include phytophthora-tolerant cultivars, Aristotle and Paladin, as well as phytophthora-susceptible cultivars Camelot and Alliance (Rutgers University, 2005). Additionally, bell pepper fields in this region are often rotated with cucurbit crops such as summer squash (Cucurbita pepo) or cucumber (Cucumis sativus) or solanaceous crops such as eggplant (Solanum melongena) or tomato (Solanum lycopersicum), which also are susceptible to the pathogen. Because of poor crop rotations and the repeated use of the fungicide, mefenoxam, insensitive strains of P. capsici have developed on some vegetable farms in southern New Jersey (Fogg and Johnston, 2003; Parra and Ristaino, 2001). Since the early 1990s, researchers in the state have cooperated with commercial breeders and seed companies to evaluate bell pepper breeding lines and cultivars under field conditions in southern New Jersey to identify those breeding lines or cultivars which exhibit field tolerance to local isolates of P. capsici. Results of these studies have led many vegetable growers in southern New Jersey to plant phytophthora-tolerant bell pepper cultivars over the past decade.
Importantly, observations made during these research evaluations over the past decade have determined that some cultivars or breeding lines with resistance or tolerance to the crown rot phase of phytophthora blight have exhibited what is now referred to as skin separation, or “silvering,” of bell pepper fruit (Fig. 1). Although only cosmetic in nature, skin separation is a disorder that reduces aesthetic fruit quality in bell pepper. Skin separation has been generically defined as a “silvery white discoloration,” which appears as “diffused or solid silvery white areas” on fruit. Because it is considered a “defect” by USDA grading standards, skin separation could potentially be used to reduce the grade of fruit (USDA, 2005). Because resistant and/or tolerant cultivars make up as much as 30%–40% of the bell pepper acreage in southern New Jersey, many growers are at a potential risk for reduced fruit quality and grade rejection due to the presence of skin separation (Rutgers University, 2005). In some years in New Jersey, incidence of skin separation has been estimated to be as high as 66% on some harvest dates in some phytophthora-tolerant cultivars and breeding lines (Wyenandt and Kline, 2006b). Preliminary research on the possible relationship between phytophthora resistance and the development of skin separation suggests that environmental factors and cultural practices may also influence the amount of skin separation development in bell pepper fruit (Wyenandt and Kline, 2006a; Wyenandt et al., 2007). Additionally, given the increasing costs of crop production (e.g., fertilizer costs) in the United States, bell pepper growers need to know if recommended N rates and/or newly developed nitrogen additives will be cost effective and have any influence on the development of skin separation in bell pepper fruit.
The objectives of this research were to determine the effects of six nitrogen fertility programs and two commercial bell pepper cultivars with or without tolerance to the crown rot phase of phytophthora blight on marketable yield and incidence of skin separation in fruit of bell pepper.
Alley, M., Binford, G., Phillips, S. & Osmond, D. 2006 Agricultural management of enhanced efficiency fertilizers: Eastern coastal states Proc. Amer. Soc. Agron., Crop Sci. Soc. Amer., Soil Sci. Soc. Amer. Abstr. 97.
Dainello, F.J. 2006 Nitamin fertilizer increases marketable yield and crop quality in tomato studies Texas Coop. Ext. Veg. Production Mktg. News 16 1 2
Glosier, B.R., Ogundiwin, E.A., Sidhu, G.S., Sischo, D.R. & Prince, J.P. 2008 A differential series of pepper (Capsicum annuum) lines delineates fourteen physiological races of Phytophthora capsici Euphytica 162 23 30
Kelley, W.T. 2005 Additional research on the use of Nitamin in bell pepper production 23 25 Kelley W.T. & Langston D.B. Georgia vegetable extension research report 2005 Univ. Georgia Coop. Res. Ext. Publ. 5-2006
Monroy-Barbosa, A. & Bosland, P.W. 2008 Genetic analysis of phytophthora root rot race-specific resistance in chili pepper J. Amer. Soc. Hort. Sci. 133 825 829
Orton, T.J. 2011 Commercial Vegetable Production Recommendations Rutgers Coop. Ext. Publ. E001. 19 Mar. 2011 <http://www.njveg.rutgers.edu/html/gc-2production-guide.html>.
Parra, G. & Ristaino, J.B. 2001 Resistance to mefenoxam and metalaxyl among field isolates of Phytophthora capsici causing phytophthora blight of bell pepper Plant Dis. 85 1069 1075
Ristaino, J.B. & Johnston, S.A. 1999 Ecologically-based approaches to management of phytophthora blight in bell pepper Plant Dis. 83 1080 1089
Rutgers University 2005 Crop Profile for Bell Peppers in New Jersey 19 Mar. 2009 <http://www.pestmanagement.rutgers.edu/NJinPAS/CropProfiles/NJPpeppercp05.pdf>.
Sy, O., Steiner, R. & Bosland, P.W. 2008 Recombinant inbred line differential identifies race-specific resistance to phytophthora root rot in Capsicum annuum Phytopathology 98 867 870
U.S. Department of Agriculture 2005 United States Standards for Grades of Sweet Peppers 23 Mar. 2011 <http://www.ams.usda.gov/AMSv1.0/getfile?dDocName=STELPRDC5050318>.
U.S. Department of Agriculture 2011 Vegetables Summary 2011 23 Mar. 2011 <http://usda.mannlib.cornell.edu/usda/current/VegeSumm/VegeSumm-01-27-2011.pdf>.
Wyenandt, A. & Kline, W.L. 2006a Effects of cultivar and production system on the development of skin separation (silvering) in bell pepper fruit in New Jersey Phytopathology 96 S125 (abstr.).
Wyenandt, C.A. & Kline, W.L. 2006b Evaluation of skin separation (silvering) in fruit of bell pepper cultivars HortScience 41 494 (abstr.).
Wyenandt, C.A., Kline, W.L., Ward, D.L., Sudal, J.F. & Maxwell, N.L. 2007 Relationship between skin separation and phytophthora-resistance in bell pepper cultivars and breeding lines Phytopathology 97 S125 (abstr.).